Yeast

Yeast is a single-celled organism used extensively in cooking, particularly in baking and brewing, due to its ability to ferment sugars and produce carbon dioxide and alcohol. This fermentation process is what makes yeast invaluable in culinary applications. Here's how yeast is commonly used in cooking:

Leavened Breads:

Yeast is most famously used in bread-making. It ferments the sugars present in the dough, producing carbon dioxide gas that gets trapped in the gluten network of the dough, causing it to rise and creating the light, airy structure of bread.

Pizza Dough:

Similar to bread, yeast is used in pizza dough to provide the rise that makes the crust light and chewy. The fermentation process also contributes to the development of flavor in the dough.

Pastries:

Certain pastries, such as croissants and Danish pastries, use yeast to help the dough rise and create layers of flaky, tender pastry.

Sweet Breads and Rolls:

Yeast is used in sweet breads like cinnamon rolls, brioche, and panettone, where it not only helps the dough rise but also contributes to the rich, tender texture.

Brewing:

Yeast is crucial in the brewing of beer and the production of wine. In beer making, yeast ferments the sugars from malted grains to produce alcohol and carbon dioxide, which carbonates the beer. In winemaking, yeast ferments the natural sugars in grapes to produce alcohol.

Ethanol Production:

On an industrial scale, yeast is used to ferment biomass into ethanol, which can be used as a biofuel.

Non-Alcoholic Fermented Beverages:

Yeast is used in the production of non-alcoholic fermented beverages like kombucha (although kombucha also involves a bacterial component), ginger beer, and root beer.

Sourdough:

While sourdough relies on wild yeasts and bacteria present in the environment, the principle is similar, with the yeast fermenting the sugars in the dough to create rise and flavor.

Nutritional Supplements:

Nutritional yeast, a deactivated form of yeast, is used as a dietary supplement and flavoring agent, particularly in vegan and vegetarian cooking. It has a cheesy, nutty flavor and is rich in vitamins, minerals, and proteins.

When using yeast in cooking, especially for baking, it's important to "proof" active dry yeast by dissolving it in warm water (sometimes with a pinch of sugar) to ensure it's alive and active before adding it to the dough. Instant yeast can be mixed directly with dry ingredients. The temperature of the liquids and the dough is crucial, as too high a temperature can kill the yeast, while too low a temperature can slow down its activity. The fermentation time also significantly affects the flavor and texture of the final product, with longer fermentation times typically resulting in more complex flavors.